Anyone walking a path blazed by Thoreau should tread carefully. His observations about nineteenth-century American civilization are sometimes laced with provocation. “If we read of one man robbed, or murdered, or killed by accident, or one house burned, or one vessel wrecked, or one steamboat blown up, or one cow run over on the Western Railroad, or one mad dog killed, or one lot of grasshoppers in the winter,—we never read of another,” he wrote in Walden. “One is enough. If you are acquainted with the principle, what do you care for a myriad instances and applications?” Yet Thoreau lived during a period of tumultuous change. The nascent promise of scientific empiricism in the sixteenth century was finally achieved in the Industrial Revolution of the nineteenth, the innovations of which helped spread the American empire and the mechanized urban sensibility that Thoreau’s musings on borrowed land were meant to stand against. The Transcendentalists could not help being swept up in the political movements delivered by newspapers and telegraph to their hamlets. Thoreau recognized the implicating force of world affairs during a break from his isolation when he traveled into town to retrieve his mended shoe from a cobbler. A meek tax collector approached him. Wanting no part in Southern slavery and the war in Mexico, Thoreau refused to pay and demanded the collector escort him to jail. Months after his release, he gave the speech that would become “Civil Disobedience.”

As Thoreau described it, civil disobedience involved nurturing one’s own sense of justice, no matter what anyone else thought or how obnoxious you became. (The civil rights movement added the revolutionary concept of community identity.) He founded the idea on a strong sense of self. Living by the pond after his arrest, he decided that people should treat themselves like landscapes. “Be a Columbus to whole new continents and worlds within you, opening new channels, not of trade, but of thought,” he wrote. Through those new channels, each person could shun the laws of society, because he would discover “the laws of his being.” But the nineteenth century progressed in a way that changed ideas about human nature. Machines were made, slaves were freed, and Charles Darwin wrote On the Origin of Species and TheDescent of Man. Even Emerson, after rowing down a river with Thoreau one night, wrote in his journal that nature was just “animated geometry.” In the wake of the republican revolutions in Europe and the US Civil War, the rarefied terminology of science had become common parlance. As the historian Jonathan Sperber has pointed out, Karl Marx, a devoted Hegelian, let Friedrich Engels sell their theories to the public in the language of positivism and empiricism that Darwinists helped to spread, though empiricism was the very ideology that Hegel had originally set out to criticize. Inspired by Darwin, people began to see their minds as evolving. Later, with the help of Freud, they could intervene directly and attempt to restructure their consciousness. Lilly often wrote that psychoanalysis worked well alongside the reprogramming methods he outlined in his books. “Know thyself” was no longer the motto of thoughtful people. Now, fully postindustrial, it had become “Engineer thyself.”

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Just as the language of empiricism spilled across the United States in the nineteenth century, the language of information technology has seeped from government laboratories like Lilly’s into contemporary life. Floaters today talk about the pleasures of “unplugging,” “recharging,” “hitting the ‘reset’ button” or “shutting down.” A recent issue of Fast Company demanded that we “#Unplug,” and the web version of its cover story, which is about one man’s twenty-five-day disconnect, frames itself with illustrations of yellow flowers and grassy cliffs that overwhelm the screen as you scroll down. (There is an option to “Turn Off Nature.”) That the language of information technology pervades their understanding of freeing themselves from its perceived harms is not unique to them. Thoreau borrowed from the terminology of science, referring to his isolation as an “experiment.” But while Thoreau and the floaters have escaped in similar ways from the pressures of civilization, Thoreau wanted to “burst forth a more perfect creature, fitted for a higher society.” The kind of mind that dreams up “Civil Disobedience” believes in cultivating a psyche prepared to live in a society that does not yet exist, and to resist indignantly the one that does. Powers calls the Walden experiment a withdrawal “within the world,” but he overlooks the utopian aspirations of Thoreau’s experiment. There’s nothing transcendent about making yourself comfortable within the world’s limits.

Many floaters more readily align with Powers’s mistaken description of Thoreau. Rather than use the tanks to escape from society, they isolate themselves to escape toward society. Floaters are happy to have the anxious aspects of themselves reprogrammed into a sociable tranquility, especially those afflicted by serious mental wounds, like military veterans who hope sensory deprivation will help treat their PTSD. (One Float On employee told me she believes that if prisoners were given the opportunity to float, they would become much more “manageable” and prison violence would likely decrease.) When the solution serves too well, some floaters pragmatically impose limits on the relief they seek. Andrew, the “human firewall” consultant, told me he used to book sessions in the morning before work but had to stop. “I found myself being much more understanding and sympathetic and I let a lot more things slide,” he explained. “It was then that I realized I needed to stop floating in the morning or I’d start allowing people’s excuses—and projects would get delayed and pretty soon none of us would have a job.”

One wonders if, in a hundred years, the tacit philosophy of the floaters who accept the world as it is and change themselves instead could improve society. Robert and Edward Skidelsky, the father-and-son economic historians who wrote the book How Much Is Enough? (2012), believe that there is something worth reprogramming in us: not the parts of our brains shaped by digital technology, but the drive to work too much. If only more schools, against our avaricious natures, taught us to be leisurely, those who labor pointlessly for more and more capital would relax instead of working overtime, and more wealth would become available to those who need it. The income gap would shrink.

Turkle also worries about a type of overwork, one that especially affects adolescents in the digital age. She thinks kids need more space for leisure, but unlike the Skidelskys, she is not as much concerned with economic equality as she is with the freedom to self-develop. On National Public Radio, she argued that the transition from anonymity in early Internet chatrooms to the curated exhibitionism of Facebook has turned the “playful self-exploration” of growing up into “consequential work.” In social media, adolescents find their trivial activities recorded and made available for scrutiny by peers, potential employers and college admissions officers alike. Perhaps teenagers should retire from their bright, crowded screens for a while and learn to have fun with themselves in the dark.

One evening during a break from tank construction, Quinn Zepeda told me he studied Transcendentalism in a college ethics course. He agreed that sensory deprivation can be used as a balm against the caustic elements of civilization—although, he was quick to add, he would rather not sit by a pond: “Staying in my room with the door closed would be my version of going out into nature.” He prefers to lie beneath “the stars on the ceiling that take in the light from the day and then shine for you at night.” When I asked him whether he ponders transcendental ideas during his floats, he said, in a Thoreauvian tone, “I have my own kind of philosophies. A lot of time I want to escape the thought train as much as possible.” Talley, his colleague and friend, had told me his life in the dark ran just the opposite: he thinks a lot in the tank. He alluded to “intense experiences.” I pressed him to tell me where his mind went in that soundproof room and he paused, as though imagining his words broadcast across wires and satellites. “I think that might be a little personal for an interview,” he said. “Come on by later, if you want. We can sit down and I’ll tell you all about it.”